feat: adds github workflow to create an ironic esp image

.github/workflows/build-ironic-esp-image.yaml

@@ -0,0 +1,49 @@
+---
+name: build-ironic-esp-image
+
+on:
+  workflow_dispatch:
+  pull_request:
+    paths:
+      - 'ironic-images/**'
+  push:
+    branches:
+      - main
+    paths:
+      - 'ironic-images/**'
+  merge_group:
+    types: [checks_requested]
+
+jobs:
+
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Install Dependencies
+        run: sudo apt update && sudo apt install -y grub-efi-amd64-signed shim-signed mtools
+
+      - name: Create esp image
+        run: |
+          cp /usr/lib/shim/shimx64.efi.signed /tmp/bootx64.efi
+          cp /usr/lib/grub/x86_64-efi-signed/grubnetx64.efi.signed /tmp/grubx64.efi
+          dd if=/dev/zero of=/tmp/esp.img bs=4096 count=1024
+          mkfs.msdos -F 12 -n ESP_IMAGE /tmp/esp.img
+          mmd -i /tmp/esp.img EFI EFI/BOOT
+          mcopy -i /tmp/esp.img -v /tmp/bootx64.efi ::EFI/BOOT/BOOTX64.efi
+          mcopy -i /tmp/esp.img -v /tmp/grubx64.efi ::EFI/BOOT/GRUBX64.efi
+          mdir -i /tmp/esp.img ::EFI/BOOT
+
+      - name: Set timestamp environment variable
+        run: echo "TIMESTAMP=$(git show --no-patch --no-notes --pretty='%cd' --date=format:'%Y%m%d%H%M%S' ${{ github.sha }})" >>  $GITHUB_ENV
+
+      - name: Publish Release
+        id: create_release
+        uses: softprops/action-gh-release@e7a8f85e1c67a31e6ed99a94b41bd0b71bbee6b8 # v2
+        with:
+          name: understack-esp-images
+          tag_name: understack-esp-images-${{ env.TIMESTAMP }}
+          make_latest: true
+          fail_on_unmatched_files: true
+          files: /tmp/esp.img
+        if: ${{ github.ref == 'refs/heads/main' }}